1. Field of the Invention
The present invention relates to a wireless transmission device, and more particularly, to a wireless transmission device capable of transmitting media from multiple channels.
2. Description of the Prior Art
With the development of wireless transmission technology, wireless communication applications have become more and more widely used in every aspect of life. As well as wireless network and wireless communication, the technology has applications in the field of multimedia. A conventional Audio/Video (A/V) facility has at least a media source, ex. Cable TV source, VCD player or DVD player, and a display device for displaying the media such as a cathode ray tube (CRT) television, liquid crystal display (LCD) television, plasma display panel (PDP) television, projector, etc. Since the media source and the display device are generally not situated far from each other, a substantial signal line is used for short distance connection.
Recently, however, the chances that the media source and the display device will be situated in two places far away from each other have become more common, due to user preference or certain requirements. For instance, when a user wants to watch a movie on their personal computer in their room but the movie is played through a DVD player in the sitting room, a conventional connection method using a substantial signal wire will require a much longer signal wire or may even be unachievable. Another aspect of this situation is that conventional physical connection of signal wires results in the problem of untidy complicated wiring. Hence the emergence of wireless A/V transceivers effectively solves the above-mentioned problem by using wireless transmission technology as an A/V signal transmission media between the media source and the display device.
Please refer to FIG. 1, which is a functional diagram of a prior art wireless A/V transceiver 10. The wireless A/V transceiver 10 comprises an A/V transmitter 20 and an A/V receiver 60. The A/V transmitter 20 comprises an A/V modulator 22, a mixer 24, a channel selector 26, a radio frequency amplifier 28 and a signal transmitter 30. The A/V receiver 60 comprises an A/V demodulator 62, a mixer 64, a channel selector 66, a radio frequency low noise amplifier (RFLNA) 68, a signal receiver 70 and a bandpass filter 72. Firstly, one input end of the A/V transmitter 20 receives A/V signals from an A/V source and the A/V modulator 22 modulates the A/V signals. Then the channel selector 26 generates a high frequency of 2.4 GHz and modulates the base band audio and video signals to the 2.4 GHz frequency band, and the radio frequency amplifier 28 and the signal transmitter 30 transmit the A/V content in the form of radio signals. The other input end of the A/V receiver 60 receives the radio signals of A/V content with the signal receiver 70 and the RFLNA 68. Then the channel selector 66 and the mixer 64 down convert the A/V content at a high frequency of 2.4 GHz to base band A/V signals, the bandpass filter 72 filtering out noise of the base band signals, and finally the A/V demodulator 62 demodulates the base band A/V signals into separate audio and video signals acceptable for media players. In summary, the physical signal wire is replaced by the radio signals of a 2.4 GHz frequency band.
Please refer to FIG. 2 for a functional diagram of a prior art wireless A/V transceiver 15 with TV tuner 50. If the A/V transceiver 15 further provides a function of broadcasting Cable TV signals, then the TV tuner 50 demodulates the inputted Cable TV signals into a video signal and an audio signal and transmits the demodulated A/V signals through the prior art A/V transmitter 20 in the form of radio signals.
Even with these improvements, a prior art A/V transceiver 10 or an A/V transceiver 15 with TV tuner 50 can only transmit one set of A/V signals at one time via radio transmission. In most countries, radio communication transmission in the Industrial, Science and Medical frequency band (ISM band) is regulated by being commonly divided into four segments under the consideration of allowed continuous bandwidth and A/V signal requirement, which means four practical channels are used for radio transmission in the ISM band. But the prior art wireless A/V transceiver 15 cannot concurrently transmit four different sets of wireless A/V signals with only one A/V transmitter 20. If four segments of the bandwidth of ISM band are to be fully used for four different A/V signals, four separate wireless A/V transceivers 15, i.e., four separate sets of A/V transmitters 20 and A/V receivers 60, become a necessary requirement. The difficulties of realizing such a complicated input-output wiring configuration, and the great expense involved, means that this is not a practical option.